βορβόρῳ δ' ὕδωρ λαμπρὸν μιαίνων οὔποθ' εὑρήσεις ποτόν → once limpid waters are stained with mud, you'll never find a drink
momentary: P. and V. ὁ παραυτίκα, ὁ αὐτίκα, P. ὁ παραχρῆμα.